Polymerization processes produce polymer product, often referred to as “polymer fluff”, which in many cases can be subsequently further processed in an extruder to produce polymer pellets. Components fed to the extruder may include the polymer fluff and optional additives which are added to the polymer fluff to impart desired characteristics (e.g., certain mechanical, physical, and melt properties) to the extruded polymer pellets. The extruder, also equivalently known as a pelletizer, can convey, heat, melt, and cut the extruder feed, and the molten polymer mixture can be extruded (e.g., via a twin screw extruder) through a pelletizing die under select pressure to form the polymer pellets. The extruded polymer pellets are typically cooled (e.g., in air or water) at or near the discharge region of the extruder.
The extruded polymer pellets may then be transported to a product load-out area for further processing comprising storing, blending with other pellets, and/or loading into railcars, trucks, bags, supersacks, or other containers for distribution to customers. In pellet transport systems which utilize transfer lines to move the pellets from the extruder to the load-out area, knowing the flow rate of the polymer pellets in the transfer line is desirable. The prior art suffers from the limitations of incomplete or inaccurate knowledge of the rate from the extruder, which is used to determine the appropriate amount of stabilizer or other additive to feed to the extruder. The inventions described in the present disclosure are an improvement over the prior art.